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Math Help - Vector question

  1. #1
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    Vector question

    Hi
    I need help on the following question:
    Given the points A(3,2,-1) and B(1,5,2) find the unit vector \vec  b=\frac{b}{|b|}

    I have found out that a=3i+2j-k & b=i+5j+2k

    P.S
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  2. #2
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    Quote Originally Posted by Paymemoney View Post
    Hi
    I need help on the following question:
    Given the points A(3,2,-1) and B(1,5,2) find the unit vector \vec  b=\frac{b}{|b|}

    I have found out that a=3i+2j-k & b=i+5j+2k

    P.S
    |\mathbf{b}| = \sqrt{1^2 + 5^2 + 2^2}

     = \sqrt{1 + 25 + 4}

     = \sqrt{30}


    So \frac{\mathbf{b}}{|\mathbf{b}|} = \frac{\mathbf{i} + 5\mathbf{j} + 2\mathbf{k}}{\sqrt{30}}

     = \frac{1}{\sqrt{30}}\mathbf{i} + \frac{5}{\sqrt{30}}\mathbf{j} + \frac{2}{\sqrt{30}}\mathbf{k}

     = \frac{\sqrt{30}}{30}\mathbf{i} + \frac{\sqrt{30}}{6}\mathbf{j} + \frac{\sqrt{30}}{15}\mathbf{k}.
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